Adultery is a grounds for divorce in New York, as defined in the New York Domestic Relations Law. It is a fault-based ground, meaning one spouse must prove the other committed adultery to obtain a divorce. Evidence of adultery can include witness testimony, photographs, admissions by the adulterous spouse, or circumstantial evidence. If proven, adultery can lead to a fault-based divorce, impacting spousal support and child custody arrangements. Defenses include consent, connivance, and recrimination.